COLUMBIA RIVER FLOW AND DROUGHT SINCE 17501

ABSTRACT: A network of 32 drought sensitive tree‐ring chronologies is used to reconstruct mean water year flow on the Columbia River at The Dalles, Oregon, since 1750. The reconstruction explains 30 percent of the variability in mean water year (October to September) flow, with a large portion of unexplained variance caused by underestimates of the most severe low flow events. Residual statistics from the tree‐ring reconstruction, as well as an identically specified instrumental reconstruction, exhibit positive trends over time. This finding suggests that the relationship between drought and streamflow has changed over time, supporting results from hydrologic models, which suggest that changes in land cover over the 20th Century have had measurable impacts on runoff production. Low pass filtering the flow record suggests that persistent low flows during the 1840s were probably the most severe of the past 250 years, but that flows during the 1930s were nearly as extreme. The period from 1950 to 1987 is anomalous in the context of this record for having no notable multiyear drought events. A comparison of the flow reconstruction to paleorecords of the Pacific Decadal Oscillation (PDO) and El Nino/Southern Oscillation (ENSO) support a strong 20th Century link between large scale circulation and streamflow, but suggests that this link is very weak prior to 1900.     

系统安全性与可靠性分析的故障树方法

探讨了大型复杂系统安全性与可靠性分析的故障树技术。阐述了国外具有代表性的几种建树方法。针对实际应用情况,提出了将建树过程划分为5个阶段,应遵循的8条基本准則。导出了典型系统可靠度与故障率等可靠性参数计算的通用公式。论述了故障树分析方法的特点及发展动向。     

TREE-RING RECONSTRUCTION OF UPPER GILA RWER DISCHARGE1

ABSTRACT: Effective planning for use of water resources requires accurate information on hydrologic variability induced by climatic fluctuations. Tree-ring analysis is one method of extending our knowledge of hydrologic variability beyond the relatively short period covered by gaged streamflow records. In this paper, a network of recently developed tree-ring chronologies is used to reconstruct annual river discharge in the upper Gila River drainage in southeastern Arizona and southwestern Arizona since A.D. 1663. The need for data on hydrologic variability for this semi-arid basin is accentuated because water supply is inadequate to meet current demand. A reconstruction based on multiple linear regression (R²=0.66) indicates that 20th century is unusual for clustering of high-discharge years (early 1900s), severity of multiyear drought (1950s), and amplification of low-frequency discharge variations. Periods of low discharge recur at irregular intervals averaging about 20 years. Comparison with other tree-ring reconstructions shows that these low-flow periods are synchronous from the Gila Basin to the southern part of the Upper Colorado River Basin.     

机械行业安全管理评价模式研究

安全管理评价模式繁多在各行业中得到广泛的应用。笔者运用安全工程的基本理论,基于MORT和SMORT方法,从综合及具体管理两方面提出10项影响企业安全水平的管理因素,并对该类因素进行层次分析,开发一套机械行业的安全管理评价模式;采用问卷形式对该评价模式进行了测试,选择重庆市3家有代表性的机械企业,运用层次分析法对测试结果进行计算分析,验证安全管理评价模式的有效性和可行性,并对企业的安全管理提出了建议。     

工程系统一体化安全风险模型研究

借鉴功能模拟原理,利用目标树-成功树-主逻辑图(GTST-MLD)框架,提出了一个一体化安全风险模型。该模型对关联于工程系统安全特性的目标、功能、结构、行为等因素予以综合,提供了从多层次研究解决安全问题的模型基础,克服了基于事件树/故障树模型的概率风险评估等传统方法而分别对系统结构、行为、事件进行研究的问题,支持实现在更高的系统功能层面上对系统安全性的分析研究。通过研究该模型在安全风险评估、事故因果关联分析、潜在交互作用鉴别中的应用,表明研究成果为解决复杂工程系统安全问题提供了新的分析手段。     

小型尾矿库存在的问题及溃坝事故树分析

在对20家小型尾矿库现场检查和安全评价的基础上,分析了尾矿库安全管理和安全评价工作中存在的问题,应用事故树分析法对尾矿库溃坝事故进行了具体分析.     

大型公共场所火灾风险评价指标体系(Ⅰ)--火灾事故因果分析

选择1998—2004年《中国火灾统计年鉴》中大型公共场所特大火灾事故的案例76起，结合事件树、故障树分析方法，分析了我国大型公共场所火灾事故的原因，得出了大型公共场所火灾事故因果分析图。     

家户水灾社会脆弱性的评估方法研究——以长沙地区为例

中国是洪水灾害发生频繁的国家之一，研究水灾脆弱性对中国的灾害风险管理有着极为重要的意义。但是，合理评估脆弱性尤其是社会脆弱性却面临着极大的挑战。利用Hoovering改进模式，选择湘江流域的长沙地区为研究区，对研究区内的家户进行了社会脆弱性评价。结果表明，长沙市区的5个区内，高脆弱性家户最多的是天心区，最少的是雨花区。而就社区而言，高脆弱性家户最多的足裕南街街道和桔子洲街道。该结果反映了长沙不同行政区、社区社会脆弱性的差别，可供确定受援地区和受援人群及开展援助活动，乃至灾后日常风险管理参考。     

The Decision-Identification Tree: A New NEPA Scoping Tool

decision-based scoping —provides an effective methodology for improving the EIS scoping process. Decision-based scoping, in conjunction with a new tool, the decision-identification tree (DIT), places emphasis on first identifying the potential decisions that may eventually need to be made. The DIT provides a methodology for mapping alternative courses of action as a function of fundamental decision points. Once these decision points have been correctly identified, the range of actions, alternatives, and impacts can be more accurately assessed; this approach can improve the effectiveness of EIS planning, while reducing the risk of future disconnects between the EIS analysis and reaching a final decision. This approach also has applications in other planning disciplines beyond that of the EIS.     

紫外光协助下DSA电极对1,4-苯醌的强化开环作用研究

以商品化DSA电极为光电极,以1,4-苯醌为模型污染物进行了光电催化降解,考察了外加电解质、外加电场强度和初始pH条件等因素的影响.结果表明,光电催化氧化过程的TOC去除率是单独光催化氧化和电催化氧化过程之和的1.25倍,光电催化降解过程具有更高的降解效率,证明光催化氧化和电催化氧化过程的耦合产生了一定的协同作用.外加电解质和外加电场均能在一定浓度和强度范围内有效提高光电催化降解效率.酸性和中性pH条件利于1,4-苯醌的开环矿化.探讨了光电催化氧化机制,指出以电化学氧化作用为主导的光助电催化氧化过程能够高效产生羟基自由基,降解效率可调,在水处理中更具实用价值.